Alloy and process of making the same



Patented Mar. 20, 1923.

UNITED STATES PATENT OFFICE.

FREDERICK T. McCURDY, 0F KOKOMO, INDIANA, ASSIGNOR TO HAYNES STELLITECOMPANY, A CORPORATION OF INDIANA.

ALLOY AND PROCESS or MAKING THE SAME.

Ho Drawing.

T o (IZZ- whom it may concern Be it known that I, FREDERICK T. Mo-CURDY, a citizen of the United States, re siding at Kokomo, in thecounty ofHoWard and State of Indiana, have invented certain new anduseful Improvements in Alloys and Processes of Making the Same, of whichthe following is a specification.

The presence in metal alloys of substantial proportions of cobalt andone or more metals of the chromium group (chromium, tungsten, molybdenumand uranium) is known to impart remarkable properties to such alloys. Ingeneral, the alloys are highly resist-ant to oxidation and othercorroding influences, are hard, strong and elastic, and capable oftaking a fine cutting edge, and when worked up into cutting tools, forexample lathe tools, preserve their hardness and edge at remarkably hightemperatures, thus permitting the use of very high cutting speeds.Alloys of the type referred to are disclosed, for example, in thepatents to Elwood Haynes, No. 873,745, December 17, 1907, No. 1,057,423,April 1, 1913, No.'1,057,- 828, April 1, 1913 and No. 1,150,113, August17, 1915.

I have found that the properties of alloys containing cobalt and one ormore chromium group metals may be much improved by the addition oftantalum. My new alloys may be produced by incorporating substantiallypure tantalum into a molten bath contaimng the other metals, or byadding the tantalum previously alloyed with other metals which exerciseno prejudicial effect on the final product. I prefer, however, to applythe tantalum as oxid, either the naturally-oocurring iron and manganesetantalities or the artificial pent-oxid being employed. The tantalummaterial may be added either before or after the fusion of the otherconstituents of the alloy.

Even when no reduced tantalum is used, and only oxid is added, theresulting product shows the presence of tantalum, presumably as alloyedmetal. If tantalum oxid is used, I prefer to have present in the moltenbath with which the oxid is brought into contact, one or both thereadily oxidizable elements of the carbon group (carbon and silicon) asthese appear to assist in the reduction of the tantalum oxid and theincorporation of the.

metal into the alloy. If carbon and silicon are desired in the finalproduct, due allow- Application filed June 18, 1921. Serial No. 478,788.

ance mustof course be made for the quantitigs oxidized and removed bythe tantalum 0x1 While I am unable to describe the mechanism of theaction of the tantalum material, the effect on the alloy is striking.The metal is denser and finer grained in its micro-structure, while thestrength and permissible cutting speed are frequently increased by, athird of their value in an exactly similar alloy without tantalumaddition.

In a specific instance where the beneficial action of tantalum Wasmarked, two similar charges were melted, tantalum oxid equivalent to 2%of the weight of metals present being added to one charge. Each of theresulting alloys contained approximately 50% cobalt, 25% chromium and15% tungsten. The alloy produced from the charge without tantalumaddition contained 0.64% silicon and 2.22% carbon while the charge whichincluded tantalum oxid produced ametal in which silicon was reduced to0.26% and. carbon to 2.04%, tantalum being present in the metal in theamount of 1.08%.

I have obtained good results by using tantalum oxid in amounts up to 10%of the charge. If the tantalum is added as reduced metal or alloy, itmay be used in amounts varying from fractional percentages to 5%.

With respect to the constituents other than tantalum in my finishedalloys, a Wide range of proportions is permissible. Preferably cobaltand the chromium metal should each be present in an amount not less than10% of the total alloy. The compositions disclosed in the patent toHaynes, No. 1,057 ,423 referred to above, give alloys having highlydesirable properties when tantalum is added. Iron and nickel may beadded as desired to prevent excessive hardness and promote forgeability,if desired, as disclosed in Haynes No. 1,150,113.

I claim:

1. A metal alloy comprising cobalt, a metal of the chromium group, andtantalum, the cobalt and metal of the chromium group each being presentin the proportion of at least 10% and the tantalum being notsubstantially in excess of 5%.

2. A metal alloy comprising cobalt, chromium and tantalum, the cobaltand chromium each being present in the proportion of. at least 10% andthe tantalum being not substantially in excess of 5%.

the chromium group.and an element of the carbon group, into-contact W1thtantalum oxid.

6. The process which comprises bringing I a molten bath containingcobalt, chromium, another metal of the chromium group, and :r reducingagent, into contact with tantalum oxid.

In testimony whereof, I aflix'my signature.

FREDERICK T; MQCURD Y.

